A study of the molecular and cellular nature of some of the processes that occur during calcium metabolism in various avian species is now in process. Research efforts are directed primarily toward an elucidation of the role of carbonic anhydrase during normal calcification in the avian shellgland (uterus). Physical characterization of three enzyme systems (i.e. carbonic anhydrase, a magnesium dependent, bicarbonate sensitive ATPase isolated from avian oviduct, and a multienzyme aromatizing system from avian ovary) is in process. Another phase of the study probes the possible molecular effects of the environmental pollutants, DDT and DDE, on the three enzyme systems under observation in vitro. The rationale for the study centers around the assumption that a basic understanding of the action of polluting pesticides, such as the halogenated hydrocarbons DDT and DDE, on avian systems known to be sensitive, may assist in our understanding of future deleterious effects of these pollutants on other species, including man.